'If we wish to remain effective on the World stage'.
Whether we wish to or not, the question is 'can we'?. I think not. The British Bulldog is no more and we perhaps need to finally acknowledge that at the political level. We simply do not have the clout, or the financial capability, to offer ourselves up as a major world player.
We are a tiny, bankrupt, over-populated island nation off the northern coast of mainland Europe. The next few decades are going to be about basic survival, never mind flexing our muscles around the globe.
Very, very sad.